When user equipment (User Equipment, UE) is reselected from a time division duplex-synchronous (Time Division Duplex-Synchronous CDMA, TD-SCDMA) system to a long term evolution (Long Term Evolution, TD-LTE) system, a core network needs to process a tracking area update (Tracking Area Update, TAU) flow. After receiving a modify bearer request (Modify Bearer Request) message, a packet data network (Packet Data Network, PDN) gateway (PDN Gateway, PGW) updates user position information and updates the position information of a serving gateway (Serving Gate Way, SGW), meanwhile, a network element property is switched from a gateway general packet radio service (General Packet Radio Service, GPRS) support node (Gateway GPRS Support Node, GGSN) to the PGW, if the IP addresses of an S5/S8 interface between the SGW and the PGW and a Gn/Gp interface between the GGSN and a service GPRS supporting node (Service GPRS Supporting Node, SGSN) are different (e.g., the S5/S8 interface and the Gn/Gp interface are in different networks), a S5/S8 signaling plane address of the PGW will change, and user plane resources need to be reselected.
But according to a 29274 GTPC (GTP Control Plane, wherein GTP refers to a GPRS Tunneling Protocol) protocol, in a modify bearer response (Modify Bearer Response) message, the control plane and user plane address information of the PGW (a control plane IF address of an interface connecting the PGW with the SGW, a user plane IP address and a tunnel endpoint identifier (Tunnel Endpoint Identifier, TEID, including user plane TEID (TEIDU) and control plane TEID (TEIDC)) could not be responded to an SGW network element, and the SGW and a mobility management entity (Mobility Management Entity, MME) still store old GGSN/PGW addresses in instance areas in a TAU process.
Specifically, in a 23401 protocol, according to protocol description, the TAU process is specifically as follows:
1. the SGW (reselected SGW, namely, new SGW) notifies the PGW of user. equipment (User Equipment, UE) position information and change of a radio access type (Radio Access Type, RAT) type (type) through an update bearer request (Update Bearer Request) message. Wherein, the update bearer request message carries an SGW address, the TEID of the SGW side and RAT type information.2. If a dynamic policy control and charging (Policy Control and Charging, PCC) rule is configured, and the PGW needs to notify a policy and charging rules function (Policy And Charging Rules Function, PCRF) of the UE position information and the RAT type information, the PGW triggers an IP-connectivity access network (IP-Connectivity Access Network, IP-CAN) session modification flow and notifies the PCRF of the UE position information and the RAT type information,3. The PGW updates a bearer context and responds an update bearer response (Update Bearer Response) message. Wherein, the update bearer response message carries a mobile station ISDN number (MSISDN), a PGW address and the TEID of the PGW side.4. The SGW (new SGW) updates the bearer context. After receiving a protocol data unit (Protocol Data Unit, PDU) of an eNodeB (eNodeB, eNB), the SGW starts to send bearer data to the PGW.5. The SGW (new SGW) responds a create bearer response (Create Bearer Response) to the MME (reselected MME, namely new MME). Wherein, the create bearer response message carries the SGW address, the TEID of the SGW side, the PGW address and the TEID of the PGW side.
The schematic diagram of the specific flow (a TAU flow of reselecting a user from 3G to an LTE network) may be as shown in FIG. 1.
In addition, in the prior art, when the UE is switched from the TD-SCDMA system to the LTE system, if the IP addresses of the S5/S8 interface between the SGW and the PGW and the Gn/Gp interface between the GGSN and the SGSN are different (e.g., the S5/S8 interface and the Gn/Gp interface are in different networks), problems similar to those in the TAU process also exist.
Specifically, according to the protocol description, the process of switching the UE from the TD-SCDMA system to the LTE system is specifically as follows:
1. a Target (target) MME (switched MME) sends an update bearer request message to a Target SGW, wherein the update bearer request message carries an IP and an TEID allocated by a Target eNodeB to an S1-U;
2. the Target SGW sends an update bearer request to the PGW (the update bearer request carries an SGW address, TEID of an SGW side, a RAT type and APN-AMBR), after receiving the update bearer request message, the PGW updates the context thereof and sends back an update bearer response (Update Bearer Response) message. At this time, a downlink channel is switched to the target side.
If dynamic PCC is deployed, the PGW initiates an IP-CAN session modification to notify the PCRF of the changed information, for example, RAT change.
3. The Target SGW sends back the update bearer response message to the Target MME.
The schematic diagram of the specific flow (a flow of switching the user from UTRAN to the LTE network) may be as shown in FIG. 2.
Wherein, during the TAU process and the switching process described in the 23401 protocol, the Update Bearer Request/Response message, in a corresponding 29274 GTPC interface protocol, is a Modify Bearer Request/Response message.
In the 29274 GTPC interface protocol, the information of information elements (Information Elements, IE) carried in the response message (Modify Bearer Response) corresponding to the TAU flow may be as shown in table 1:
TABLE 1IE list of Modify Bearer Response messageInformationCondition/elementscomment(Information(Condition/Instanceelements)PComment)IE type (IE Type)(Ins.)Cause (Cause)MCause (Cause)0Mobile stationCMobile station0ISDNISDNnumber (MSISDN)number (MSISDN)Linked EPSCEPS bearer0bearer ID (Linkedidentifier (EBI)EPS Bearer ID)AggregateCAggregate0maximum bitmaximum bitrate (Aggregaterate (AMBR)Maximum BitRate (APN-AMBR))APNCAPN0restriction (APNrestriction (APNRestriction)Restriction)ProtocolCProtocol0configurationconfigurationoptions (Protocoloptions (PCO)ConfigurationOptions (PCO))Bearer contextsCBearer0modified (Bearercontext (BearerContextsContext)modified)Bearer contextsCBearer1marked forcontext (Bearerremoval (BearerContext)Contexts markedfor removal)Change reportingCChange reporting0action (Changeaction (ChangeReportingReportingAction)Action)CSG informationCOCSG information0reportingreportingaction (CSGaction (CSG(ClosedInformationSubscriberReportingGroup)Action)InformationReportingAction)ChargingCFully qualified0gatewaydomainname (Chargingname (FQDN)Gateway Name)ChargingCIP address (IP0gatewayAddress)address (ChargingGatewayAddress)PGW fullyCFully qualified0qualified PDNPDN connectionconnectionsettingsettingidentifier (FQ-identifier (PGW-CSID)FQ-CSID)SGW fullyCFully qualified1qualified PDNPDN connectionconnectionsettingsettingidentifier (FQ-identifier (SGW-CSID)FQ-CSID)RecoveryCRecovery (Recovery)0(Recovery)Private ExtensionOPrivate Extensionvswherein, the IE list of IE: Bearer Contexts modified in table 1 may be as shown in table 2:
TABLE 2IE list of Bearer Contexts modifiedOctets 1Bearer Context IE Type = 93 (decimal)Octets 2 and 3Length = nOctets 4Spare and Instance fieldsCondition/Informationcommentelements (Information(Condition/Instanceelements)PComment)IE Type (IE Type)(Ins.)EPS bearer ID (EPSMEPS bearer0Bearer ID)identifier (EBI)Cause (Cause)MCause (Cause)0SI interface SGW fullCFull tunnel0tunnel identifier (SIidentifier (F-SGW F-TEID)TEID)S12 interface SGWCFull tunnel1full tunnelidentifier (F-identifier (S12SGW F-TEID)TEID)S4-U interface SGWCFull tunnel2full tunnelidentifier (F-identifier (S4-USGWTEID)F-TEID)Charging IDCCharging ID0(Charging ID)(Charging ID)Bearer flags (BearerCOBearer0Flags)flags (BearerFlags)
In the process of implementing the present invention, the inventor has found that at least the following defects are present in the prior art:
according to the implementation of the existing protocol, when the UE is reselected or switched from the TD-SCDMA system to the TD-LTE system, in the following application scenarios:
1) when S5/S8 is accessed to a private network, while Gn/Gp is accessed to a public network;
2) when the SGW and the PGW are cooperatively arranged (i.e., no S5/S8 interface is displayed externally), the S5/S8 interface provides an internal IP, and the Gn/Gp interface provides an external IP address.
When the control plane/user plane resources displayed by the S5/S8 interface and the Gn/Gp interface are different, the existing protocol could not support the scenario.